In order to detect a manipulation performed by a user using a video display surface or a video projection surface as a manipulation surface, a method of imaging the manipulation surface through a camera and detecting motion of a hand or a finger of the user from a captured image is known. At this time, the manipulation surface is irradiated with two illumination lights, and thus it is possible to detect an approach degree or a contact point of the hand or the finger with respect to the manipulation surface from shapes of two shadows formed by the irradiation.
In this regard, a configuration in which, in a case in which a plurality of shadows formed by radiating light from a plurality of light sources are imaged through one camera, the camera images the shadows at a predetermined frame rate, and a different light source is selected for each frame from a plurality of light sources in synchronization with the frame rate of the camera and radiates light is disclosed in Patent Document 1.